The present invention relates generally to a refrigeration technique, and in particular but not by way of limitation, to a pure-phase-transformation and heatless (xe2x80x9cPPTandHxe2x80x9d) refrigerating process and method installation implemented by phase transformation without heat exhaustion to the outside environment.
Prior art refrigerating techniques, especially those of the vapor-compression type widely used in industrial and civilian fields, comprise simultaneous heat exhaustion to the outside environment during refrigeration, with a significantly greater amount of heat produced versus the amount of cooling generated. With regards to environmental effects, prior art refrigerating techniques represent a vicious circle of circumstances: increases in refrigeration result in more heat production, which in turn leads to an increased failure in refrigeration, which thus produces more heat. The prior art shows that lowest refrigerating efficiency occurs in the relatively large temperature difference between the vaporization temperature of the refrigerator and the environmental condensing temperature, which may lead to failure in refrigeration.
The object of the present invention is to provide a novel PPTandH refrigerating process and method of installation with a greater amount of cooling produced versus heat generated without heat exhaustion to the outside environment, and with high refrigerating efficiency.
In a PPTandH refrigerating process, the first-stage refrigeration comprises evaporation for vaporization of the liquid-state refrigerant, release of latent heat in vaporization, and generation of a refrigerating effect. The generated vapor is compressed into higher temperature gases, cooled through heat exhaustion and temperature reduction, and condensed into a liquid-state medium. The liquid-state medium is subjected to further cooling after flow restriction, followed by reabsorption of heat, thereby refrigerating through evaporation. The vapor is removed and the vapor pressure is reduced to bring the evaporation temperature to a predetermined value.
The system comprises a phase-transformation multistage refrigeration cycle of two or more stages, including a first- and a final-stage refrigeration cycle. In the first stage, a refrigerating compressor and a condenser are immersed in a liquid-state refrigerant of the next stage to have the generated heat absorbed by the vaporizing latent heat of the liquid-state refrigerant. This causes the temperature difference between the refrigerating evaporation temperature in the first refrigeration cycle and that of the condensing environment to be reduced to a value suitable to allow the first-stage refrigeration cycle to achieve normal refrigeration.
After the first stage, further steps are performed by phase transformation to refrigerate by cooling. Subsequent to refrigeration by refrigerant phase transformation. The next stages all utilize the lower temperature effect provided by the refrigeration cycle of the first stage to lower the temperature and condense the vapor generated. The vapor condensation allows recovery of the medium into a liquid state.
Finally, the refrigeration cycle is subjected to cooling methods. In every stage of this cycle, the vapor is first condensed into a liquid-state overcooled medium and allowed to flow downwardly in layers. Convection-based heat exchanging occurs next, with the evaporating vapor incessantly entering from below and moving upwardly in layers. Eventually, the vapor completely transforms into a liquid-state medium of the approximate saturation point, thereby reducing to a minimum the cooling dissipated during evaporation of the condensate. During the same stage of the cycle, the cooling provided by the refrigerant phase transformation is much greater than that dissipated in vapor liquification.
The refrigeration cycle in the final stage is done with the refrigerating effect, and the resultant cooling that the cycle produces is supplied outwardly.
The evaporation temperature of the refrigerant in each refrigeration cycle rises incrementally by stage according to the connecting sequences of the system. The result is that the refrigerant in the first stage has a low evaporation temperature, whereas the final-stage refrigerant has a high evaporation temperature.
There is also provided a PPTandH refrigerating installation system comprising a heat-insulated refrigerating compressor, a condenser connected with the compressor, a throttling device connected with the compressor, a second throttling device connected on the opposite side of the condenser through a high-pressure line, and an evaporator connected with the throttling devices through a liquid transfer line. The other end of the evaporator is connected with the compressor through a gas reflux line, thus forming the refrigeration cycle of the first stage with refrigerant filled therein.
The installation further comprises a first heat-insulated pressure vessel, a working-medium pump, a liquid transmission line, a heat-insulated gas-reflux line, a final stage evaporator, and a first-stage heat-insulated pressure vessel. The first heat-insulated pressure vessel has its bottom portion filled with liquid-state refrigerant and divided into an upper level and a lower level. The lower level is an enclosed space, with the first-stage refrigerating compressor and the condenser incorporated therein. The upper level and lower level are in communication via a liquid-level regulator, a liquid-supplementing line and an air line. At least two rows of plates, arranged in an interleaved manner for condensing the overcooled medium, are provided in the middle part of the first heat-insulated pressure vessel. The middle part forms a condensing space for repeated exploitation of the cooling effect.
A first-stage evaporator is mounted on the top part of the first heat-insulated pressure vessel, in which a final-stage evaporator is included. The working medium pump coupled to the first heat-insulated pressure vessel has a portion connected with the final-stage evaporator via liquid medium transfer lines. The final-stage evaporator is connected with the first heat-insulated pressure vessel via a heat-insulated gas-reflux line. A final-stage phase-transformation refrigerating cycle is operated by actuating the working-medium pump, introducing the refrigerant into the pump, pressurizing the refrigerant, and entering the final-stage evaporator via the liquid transfer lines. Finally, the vapor is generated after the evaporation of the refrigerant entering into the condensing space inside the first vessel via the gas reflux line, thus supplying cooling to the outside space.
The present invention has, through refrigeration, advantageously used the latent heat of the vaporization of the liquid-state medium. Instead of mechanically compressing the vapor medium in the stages of the phase-transformation refrigeration cycle following the first stage refrigeration, the present invention condenses the vapor medium by reducing its temperature through saturation. Moreover, since the cooling supplied during temperature-reducing condensation of the saturated vapor can be repeatedly exploited, the inherent cooling consumption is minimal. Further, the use of the prior vapor-compressing refrigerating techniques in producing inherent cooling results in relatively high refrigerating efficiency with minimal heat generation. Additionally, because of the small amount of heat to be consumed by the latent heat of vaporization of the liquid-state refrigerant, the refrigerating process and method of installation according to the present invention exhausts no heat to the outside environment, thus resulting in a high refrigeration efficiency.